首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   3230865篇
  免费   266437篇
  国内免费   13531篇
耳鼻咽喉   44425篇
儿科学   96677篇
妇产科学   80942篇
基础医学   518584篇
口腔科学   88727篇
临床医学   287626篇
内科学   565319篇
皮肤病学   86936篇
神经病学   276416篇
特种医学   126971篇
外国民族医学   105篇
外科学   511448篇
综合类   96167篇
现状与发展   23篇
一般理论   2156篇
预防医学   264353篇
眼科学   73747篇
药学   224126篇
  24篇
中国医学   9543篇
肿瘤学   156518篇
  2021年   54718篇
  2020年   34868篇
  2019年   57825篇
  2018年   70335篇
  2017年   53565篇
  2016年   59042篇
  2015年   73516篇
  2014年   107649篇
  2013年   172659篇
  2012年   83348篇
  2011年   81613篇
  2010年   113950篇
  2009年   119325篇
  2008年   69887篇
  2007年   71324篇
  2006年   82970篇
  2005年   78352篇
  2004年   80462篇
  2003年   71682篇
  2002年   61811篇
  2001年   102617篇
  2000年   95537篇
  1999年   95604篇
  1998年   64460篇
  1997年   62434篇
  1996年   60192篇
  1995年   55678篇
  1994年   49658篇
  1993年   46420篇
  1992年   66406篇
  1991年   62716篇
  1990年   59247篇
  1989年   58833篇
  1988年   54247篇
  1987年   52964篇
  1986年   49884篇
  1985年   50308篇
  1984年   45970篇
  1983年   42353篇
  1982年   40547篇
  1981年   38229篇
  1980年   35955篇
  1979年   36930篇
  1978年   33062篇
  1977年   30845篇
  1976年   27627篇
  1975年   26205篇
  1974年   26583篇
  1973年   25249篇
  1972年   23732篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
Intrahepatic shunt ratio was calculated from the fraction of the uptake constant and the blood background, analyzing the data of 99mTc-(Sn)-N-pyridoxyl-5-methyltryptophan (99mTc-PMT) hepatobiliary imaging by Rutland method. Shunt flow and total hepatic blood flow (THBF) were also calculated from the values for the effective hepatic blood flow (EHBF) estimated from the blood clearance technique. In 15 cases of normal volunteer, the average of the shunt ratio, shunt flow, and THBF were 18.4 +/- 5.4 (S.D.)%, 137.8 +/- 49 ml/min, and 753 +/- 83.2 ml/min, respectively. In 8 cases of chronic hepatitis, the values were 35.2 +/- 2.6%, 276 +/- 55.4 ml/min, and 794.1 +/- 119.4 ml/min, respectively. In 12 cases of liver cirrhosis, the values were 51.4 +/- 12.6%, 353.9 +/- 141.3 ml/min, and 685.6 +/- 174.8 ml/min, respectively. In cases of chronic hepatitis and liver cirrhosis, in comparison with normal cases, the values for the shunt ratio and shunt flow were significantly increased (p less than 0.001) and those for EHBF were significantly decreased (p less than 0.001), but those for THBF were not significantly altered. There was a significant inverse correlation between the shunt ratio and EHBF (r = -0.842) in all 35 cases. This method is considered to be useful for differential diagnosis, estimation of the grade of the diseases, and evaluation of pathophysiology of various diffuse liver diseases.  相似文献   
993.
This article describes the outcomes of a study involving family members of communication-impaired long-term care residents in a collaborative nursing/speech language pathology intervention designed to increase the residents' communication ability. Family members provided memorabilia and artifacts or produced audio or video tapes, for use in conjunction with a speech therapy enhancement program (STEP). Findings revealed that, despite a minimal improvement in speech ability, there was a dramatic increase in family members' satisfaction.  相似文献   
994.
Unfractionated cytokines have been shown to induce in vitro proliferation of neonatal rat Schwann cells but the nature of the mitogen(s) is not known. A mixture of rabbit antibodies specific for recombinant interleukin-1α (IL-1α) and interleukin-1β (IL-1β) inhibited Schwann cell proliferation induced by unfractionated human cytokines whereas antibodies to interleukin-2 (IL-2) and control IgG did not. However, purified human IL-1 and recombinant human IL-1α or β did not induce Schwann cell proliferation on their own.  相似文献   
995.
Summary Two contrasting cases of cervical intramedullary cavernous angioma in young female patients are reported. One patient had a 3-year course of step-wise progressive tetraparesis; at each of the five events intramedullary bleeding from a cryptic vascular malformation at C6–7 level was diagnosed by MRI. The other patient presented with one episode which led to MRI diagnosis of a vascular malformation at the C2 level. Both patients eventually underwent complete surgical excision of the angioma with subsequent steady improvement of the neurological deficit.  相似文献   
996.
997.
Carotid sonography is being performed on more than 5,000 participants in the Cardiovascular Health Study, a prospective, multicenter study of cardiovascular disease in men and women aged 65 years and older. The sonographic methods used to examine and measure the extracranial carotid arteries are described. Initial validation studies were performed on 61 subjects with a mean age of 68.6 years. Analysis of within- and between-sonographer differences and between-reader differences were performed for selected variables. In general, the mean absolute differences for within- and between-sonographer comparisons were small, with even less variability between readers. Variability was less for the common carotid artery than for the internal carotid artery. These data suggest that carotid sonography is a reliable and reproducible method for use in the study of carotid atherosclerosis in population studies.  相似文献   
998.
A 43-year-old woman suffered a blast-type injury to the head and neck. She subsequently developed bilateral internal carotid artery occlusion and bilateral anterior cerebral artery infarction not demonstrated by magnetic resonance imaging scan 24 hours after the explosion, but confirmed by a second scan 8 days after the explosion. In patients with blast-type injury to the head and neck who develop coma with a nonfocal neurological exam, the possibility of bilateral carotid artery occlusion and bilateral ischemic infarction should be considered.  相似文献   
999.
Flavonoids as medicines   总被引:1,自引:0,他引:1  
Although flavonoids have been used for a long time, many medical practitioners and pharmacists know very little about them. This article gives a few particulars of some flavonoids and plant extracts: rutin, water soluble derivatives of rutin, citroflavonoids, anthrocyanins, procyanidins, silymarin, Ginkgo biloba, Chrysanthellum indicum and Lespedeza capitata.  相似文献   
1000.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号